Workers.BlastHits: fix possible crash
Workers.BlastHits: fix possible crash

Refcount of bank blockset was increased once (in main thread)
and decreased multiple times (in each worker thread).
Currently refcount of bank is no changed.

starius/lua-npge,starius/lua-npge,starius/lua-npge,npge/lua-npge,npge/lua-npge,npge/lua-npge